Complex carbohydrates (glycoproteins and glycolipids) are present in all animal cells as both membrane-bound and secreted materials. Much recent effort has been devoted to the purification, structural analysis and function of these molecules. Four major classes of glycoproteins occur in mammals: (1) Asn-GlcNAc type: includes many enzymes, protein hormones, cell membrane receptors, immunoglobulins and other plasma proteins. (2) Ser(Thr)-GalNAc type: the mucins of the respiratory, gastro-intestinal and genito-urinary tracts, and secreted human blood group substances. (3) Ser-Xyl type: glycosaminoglycans such as the chondroitin sulfates which are believed to play a role in connective tissue formation and cell-cell interactions. (4) Hydroxylysine-Gal type: collagens and basement membranes. Glycolipids fall into two major classes, the glycosphingolipids and the glycoglycerolipids. Recent advances in the structure and biosynthesis of these molecules have indicated that we do not as yet fully understand their functions. The 1983 Gordon Conference on Glycoproteins and Glycolipids (Holderness School in Plymouth, N.H., on Aug. 1-5, 1983) hopes to review the following areas: (1) The latest developments in three-dimensional structure and the relationships between structure and function. (2) The control of Asn-GlcNAc oligosaccharide processing and synthesis. (3) Inhibition of these reactions by drugs with potentially interesting biological effects such as the prevention of metastasis. (4) The synthesis and structure of mucins with special emphasis on mucin function on epithelial surfaces. (5) The subcellular sites of glycosylation and the concept of sub-Golgi compartments. (6) The structure, synthesis and function of glycosaminoglycans. (7) The structure and function of glycosphingolipids.